Gas plating of titanium



9v H. J. HOMER 2,887,406

GAS PLATING OF TITANIUM Filed Dec. 14, 1956 6a; plated Titam'un metal to], ghee; ceramie, or synthetic substrate Metal, glass, ceramic, or

synthetic substrate INVENTOR' HOWARD J. HOMER fulm'.

ATTORNEYS GAS PLATING F TITANIUM Howard J. Homer, Dayton, Ohio, assignor to The Commltlmwealth Engineering Company of Ohio, Dayton, 0 i0 Application December 14, 1956, Serial No. 628,227

11 Claims. (Cl. 117-107) This invention is concerned with a method of plating metals, and more particularly to a method of depositing metal coatings or films of titanium.

In the use of titanium metal it has been difficult to produce metal coatings of the metal because of the difiiculty of working with it so that titanium metal coatings have not been in commercial use.

It is an object of this invention to provide a method for depositing titanium by the use of heat-decomposable titanium metal compounds.

It is a further object of the invention .to provide a method for producing a metal coating of titanium which is of substantially uniform thickness and which may be deposited upon surfaces as an adherent coextensive film or plate of titanium.

In producing titanium metal coatings in accordance with this invention, the object to be plated is placed in a suitable container or enclosure and heated by suitable means, such as by electrical resistance or the like, to a temperature sufiiciently high to decompose a heat-decomposable titanium organo compound brought in contact therewith and bring about the deposition of titanium metal onto the surface of the object. To avoid the formation of metal oxides during plating the plating enclosure or chamber is filled with inert gas such as helium, argon, neon or the like.

The container or enclosure in which the object to be plated is placed is connected to a vacuum source whereby the air is removed therefrom. Thereafter the inert gas, such as helium, argon, or neon, is introduced into the enclosure to maintain the object free of air or oxygen. This is necessary inasmuch as titanium metal readily reacts with oxygen and oxidizing agents to form titanium oxide.

Variousobjects and articles may be gas plated according to applicants invention to deposit a laye qor film of titanium metal directly onto a surface of an object, the same being capable of being subjected to a temperature of between substantially 400 F.-900 F.

The drawing illustrates in Figure 1 a bar-shaped article gas plated with titanium metal; and

Figure 2 depicts a disc which may be made of metal, glass, ceramic or plastic gas plated with titanium metal in accordance with this invention.

Different organo titanium compounds may be used which will heat decompose at relatively low temperatures to bring about the deposition of titanium metal onto the surface of the article to be plated. A suitable organo titanium compound for example is decyclopentadienyl titanium (C H Ti). When the compound is brought in contact with the heated surface the same decomposes and deposits the titanium metal thereon according to the following general equation of hydrocarbons but it is of no particular consequence inasmuch as the titanium metal is deposited during the i ied states Patent the time ranges up process. Otherorgano compounds of titanium may be used such as those having the general formula TiR or TiR wherein R represents an alkyl oraryl radical such as ethyl, methyl, phenyl, etc.

In the following examples the method of gas plating titanium metal on a surface is given by way of illustration.

Example I A metal object in the .form of adisc which has been thoroughly cleansed as by sanding is placed in a metal container which is adapted to behermetically sealed and the container connected toa vacuum pump. A vacuum of 1 mm. of mercury is maintained in the container and there is introduced thereinto helium to fill the container and surround the object to prevent the introduction of air or oxygen. Thereafter the object is heated by electrical resistance surrounding the container so as to bring the object to a temperature of approximately 600 F. and there is then introduced gaseous titanium decyclopentadienyl which is preferably introduced along with the helium as a carrier gas. The organo titanium compound comes in contact wtih the heated metal object and decomposes to deposit titaniummetal thereon.

The rate of gas flow in this instance approximates 4 liters per minute and the temperature was maintained between 500-900" F., the latter temperature being the maximum.

Example II In this example a similar plating of titanium was made using the organo titanium compound as in Example I, and wherein the same was plated on cleaned copper rods.

Example 111 In this instance the gas plating was carried out to deposit a thin coating of titanium metal on glass fibers.

The thickness of the coating of titanium metal will depend upon the timeof exposure of the object to be plated to the titanium organo compound. Ordinarily with exposures of the metal to organo titanium compound diluted with nitrogen and wherein the gas flow rate approximates 4 liters per minute and a concentration of 50% by volume of titaniumbearing gas for about 2 minutes, the film approximates 0.00006 inch. Where to 15 to 20 minutes, the plating of titallliium is accordingly thicker and approximates 0.0005 1nc In accordance with applicants invention, various articles of metal, glass, ceramic and synthetic products which are capable of standing the temperature to which the organo titanium compound will decompose may be coated with titanium metal. Further, where it is de sired to produce heat treated titanium metal the coated object may be further heated as by annealing as desired, to produce a smooth coherent coating of titanium.

It will be understood that this invention is not to be restricted to the specific examples given inasmuch as the invention obviously may be changed to employ other suitable organo titanium compounds and base materials upon which it is desired to produce a coating of titanium. Such modifications which come within the skill of those working in the art are intended to come within the scope of this invention and as further set forth in the appended claims.

What is claimed is:

1. A method of gas plating titanium on surfaces comprising enclosing the material to be plated. in a plating chamber, withdrawing the air from said chamber, introducing organo titanium compound which is: heat-decomposable into said plating chamber and in contact with the material therein to be plated, and heating said material to a temperature to cause decomposition of said organo titanium compound and deposition of the titanium metal constituent of said organo titanium compound onto the surface of said material, said organo titanium compound having the'formula T iR wherein R represents an alkyl or aryl radical.

2. A method of gasplating titanium on' surfaces which comprises establishing a source "of inert gas, enclosing the material to be plated in a plating chamber, removing the air from said chamber and filling the same with said inert gas, introducing organo titanium compound which is heat decomposable into said plating chamber and in contact with the material therein to be plated, and heating said material to a temperature to cause decomposition of said organo titanium compound and deposition of the titanium metal constituent of'said organo titanium compound onto the surface of said material, said organo titanium compound having'the formula TiR wherein R represents an alkyl or aryl radical.

3. A method of gas plating titanium on surfaces comprising enclosing the material to be plated in a plating chamber, withdrawing the air from said chamber, introducing decyclopentadienyl titanium compound which is heat-decomposable into said plating'chamber and in contact with the material therein to be plated, and heating said material to a temperature sufficient to cause decomposition of said 'decyclopentadienyl titanium compound and deposition of said titanium metal ontothe surface of said material.

4. In a method of depositing titanium on an article, the step of passing over said article vapors of organo titanium compound together with an inert carrier gas heated to a temperature sufficient to cause said vapors to decompose and the titanium metal of said organo titanium compound to be deposited onto said article, said organo titanium compound having the formula TiR wherein R represents an alkyl or aryl radical.

5. In a method of depositing titanium on an article, the step of passing over said article vapors of organo titanium compound together with an inert carrier gas heated to a temperature of about 400-900" F. sufficient to causesaid vapors to decompose and the titanium metal of said organo titanium compound to be deposited onto said article, said organo titanium compound having the formula TiR wherein R represents an alkyl or aryl radical.

6. A method of titanium plating a metallic object which comprises the steps of heating the object to a temperature of about 600 F., vaporizing organo titanium compound, and contacting the heated object withthe vaporized organo titanium compound, said organo titanium compound having the formula TiR wherein R represents an alkyl or aryl radical.

7. A method of gas plating a metallic object with titanium which comprises the steps of heating the object to be plated in an atmosphere of dry helium, said article being heated to a temperature sufficient to cause gaseous organo titanium compound brought in contact therewith to decompose, and then contacting said heated article with said gaseous organo titanium compound while enclosed in an inert atmosphere and at substantially atmospheric pressure, said organo titanium compound having the formula TiR wherein R represents an alkyl or aryl radical.

8. A method of gas plating a metallic object with titanium which comprises the steps of heating the object to be plated in an atmosphere of dry helium, said article being heated to a temperature sufficient to cause gaseous organo titanium compound brought in contact therewith to decompose, and then contacting said heated article while retained in a dry atmosphere of inert gas with a gaseous mixture comprising helium and organo titanium compound and at substantially atmospheric pressure, said organo titanium compound having the formula TiR wherein R represents an alkyl or aryl radical.

9. A method of gas plating a metallic object with titanium which comprises the steps of heating the object to be plated in an atmosphere of dry argon gas, said article being heated to a temperature sufficient to cause gaseous organo titanium compound brought in contact therewith todecompose, and then contacting said heated article while retained in a dry atmosphere of inert gas with a gaseous mixture comprising argon and organo titanium compound and at substantially atmospheric pressure, said organo titanium compound having the formula TiR wherein Rrepresents an alkyl or aryl radical.

10. In a method of gas plating a substrate wherein the substrate is heated in an enclosure and subjected to gaseous metal compound, the step of evacuating the said enclosure and subjecting the substrate while heated to gaseous titanium decyclopentadienyl to cause decomposition of said titanium decyclopentadienyl and deposition of titanium onto the surface of said substrate.

11. An article of manufacture made in accordance with the process of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS 2,685,535 Nack s Aug. 3, 1954 2,710,817 Castor June 14, 1955 2,780,553 Pawlyk Feb. 5, 1957 FOREIGN PATENTS 742,304 Great Britain Dec. 21, 1955 OTHER REFERENCES I 'Appl. Chem, vol. 1, pages 400406, September 1951, 260429T.

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1. A METHOD OF GAS PLATING TITANIUM ON SURFACES COMPRISING ENCLOSING THE MATERIAL TO BE PLATED IN A PLATING CHAMBER, WITHDRAWING THE AIR FROM SAID CHAMBER, INTRODUCING ORGANO TITANIUM COMPOUND WHICH IS HEAT-DECOMPOSABLE INTO SAID PLATING CHAMBER AND IN CONTACT WITH THE MATERIAL THEREIN TO BE PLATED, AND HEATING SAID MATERIAL TO A TEMPERATURE TO CAUSE DECOMPOSITION OF SAID ORGANO TITANIUM COMPOUND AND DEPOSITION OF THE TITANIUM METAL CONSTITUENT OF SAID ORGANO TITANIUM COMPOUND ONTO THE SURFACE OF SAID MATERIAL, SAID ORGANO TITANIUM COMPOUND HAVING THE FORMULA TIR WHEREIN R REPRESENTS AN ALKYL OR ARYL RADICAL. 